基于离散单元法的水平圆盘式精量排种器排种仿真试验

为了优化水平圆盘式精量排种器的最佳排种性能参数(动排种盘转速、动排种盘厚度、型孔圆角半径),达到提高粒距合格指数、降低漏播和重播指数指标,并降低大田试验强度。该文基于离散单元法对根据全膜双垄沟播技术所设计的水平圆盘式精量排种器进行了排种数值模拟,并得到玉米籽粒模型排种、重播、漏播的形成过程;为提高其排种性能,进行了排种仿真试验。仿真结果表明:以合格指数较高为重点、兼顾重播指数和漏播指数较低的原则,确定了动排种盘转速为17 r/min、动排种盘厚度为6 mm、型孔上边倒圆角半径为1 mm时为较优组合,此时粒距合格指数S=97.05%、重播指数D=1.83%、漏播指数M=1.12%。田间验证试验表明:在上述条件下,测得粒距合格指数为S=95.13%,重播指数D=2.34%,漏播指数M=2.53%,重点指标粒距合格指数误差2.02%(5%)。因此,基于离散单元法的排种器仿真试验为排种器性能参数的确定提供参考。

Simulation test for metering process of horizontal disc precision metering device based on discrete element method

In order to optimize the best metering parameters on the performance of horizontal disc precision metering device (The rate of moving metering plate, thickness of moving metering plate, fillet radius of type hole), a simulation model of horizontal disc precision metering device was designed with Solidworks. The average size of Gansu common 3 corn grains were reported in statistics, namely the length is 10.86 mm, and the width is 7.22 mm, and the thickness is 5.12mm. In accordance with which the model of corn grain was designed with the use of slice modeling techniques??, and using the spherical particles aggregation method the discrete model of corn grain was established. Poisson's ratio, shear modulus and density of corn were determined by test. Namely poisson's ratio is 0.357, and shear modulus is 2.6 MPa, density is 1 250 kg/m3. To increase the qualified index of seed space and reduce the replay and miss-seeding index, and depress the intensity of field test, on the basis of DEM dynamic simulation metering experiment of horizontal disc precision metering were conducted. Experimental results show: with higher the qualified index of seed space as the key point and taking lower the multi-seed index and the no-seed index into consideration, the bigger the qualified index of seed space is better, and the smaller the multi-seed index and the no-seed index is also better. Variance analysis showed the factor A, B and C had conspicuous effect on the qualified index of the seed space S, and the factor B had conspicuous effect on the multi-seed index D, and the factor A and C had significant influence on the no-seed index M, the factor B, interaction between A factor and C factor had a conspicuous effect on the no-seed index M. The speed of the moving metering plate is 17 r/min and the thickness of the moving seed metering plate is 6mm and the fillet radius of the type hole is 1 mm, was selected as an optimal combination. Under the conditions, the qualified index of seed space was 97.05%, and the multi-seed index was 1.83%, and the no-seed index was 1.12%. The optimized parameters of the simulation experiment were verified in the test trial. Field test results showed: under the conditions, the qualified index of the seed space was 95.13%, and the multi-seed index was 2.34%, and the no-seed index was 2.78%. In comparison with the simulation results, the error of the qualified index of the seed space was 2.02%. Therefore, simulation test of the horizontal disc precision metering device has certain guiding significance to develop the performance of the metering parameters device. It provided a reference method for optimizing the other types of precision metering.